Rick,
It came from a post-breakup interview, and he was talking about himself as a guitarist. He was pretty insecure in those days, rather strangely. None of those guys knew how to get along for the longest time and it was rather painful to watch. One of the things he said about his guitar playing was something to the effect of ask Eric Clapton, he'll tell you how good I am. Very insecure.

DZ,
Now that is a great tuba picture!

Tony,
It's not ego if you can back it up...it's not like Lennon never accomplished anything as a musician!

I think it's fair enough - not egotistical at all. If you give an instrument you invented to a really talented musician in a few minutes they'll figure out how to get a sound out of it. The similarities among instruments are much greater than the differences to experienced musicians.